Dialkyl n,n-dialkoxymethylcarbamylphosphonates

ABSTRACT

PRODUCTION OF DIALKYL N,N-DIALKOXYMETHYLCARBAMYLPHOSPHONATES BY REACTION OF DIALKYL CARBAMYLPHOSPHONATES OR THEIR N-METHYLOL OR N-ALKOXYMETHYL COMPOUNDS WITH FORMALDEHYDE FOLLOWED BY TREATMENT OF THE REACTION MIXTURE WITH ALKANOLS, AND THE NEW DIALKYL N,N-DIALKOXYMETHYLCARBAMYLPHOSPHONATES THEMSELEVES. THE NEW COMPOUNDS ARE ASSISTANTS, PARTICULARLY FLAMEPROOFING ADDITIVES, FOR SURFACE COATINGS AND PLASTICS AND VALUABLE STARTING MATERIALS FOR THE PRODUCTION OF SUCH ASSISTANTS.

United ABSTRACT OF THE DISCLOSURE Production of dialkyl N,N dialkoxymethylcarbamylphosphonates 'by reaction of dialkyl carbamylphosphonates or their N-methylol or N-alkoxymethyl compounds with formaldehyde followed by treatment of the reaction mixture with alkanols, and the new dialkyl N,N-dialkoxy methylcarbamylphosphonates themselves. The new compounds are assistants, particularly flameproofing additives, fguurface-eoatings and plastics and valuable starting materials for the production of such assistants.

The invention relates to a process for the production ofdialkyl N,N'-dialkoxymethylcarbamylphosphonates by reaction of dialkyl carbamylphosphonates or their N- methylol or N-alkoxymethyl compounds with rformaldehyde followed by treatment of the reaction mixture with alkanols, and new substances of this type.

It is known that primary carboxylic amides can be converted into N-monomethylol compounds by reaction with formaldehyde in alkaline solution (Liebigs Annalen der Chemie, 343, 207 (1905); 361, 113 (1908)). In alkaline solution the methylolamides are converted into bis-acylamidomethyl ethers (Kunststofie, 41, 221 (1951)). The reaction of N-monomethylamides with a second molecule of formaldehyde to definite N,N-dimethylolamides does not take place (Kunststofi'e, 4.1, 221 (1951)). Methylolation of amides also takes place in the presence of acids, the methylol compounds readily being converted into methylene-bis-acylamides (Liebigs Annalen der Chemie, 343, 207 (1905); 361, 113 (1908)). Conversion of the amides with formaldehyde in the presence of acids into dimethylol compounds could not be achieved.

An object of this invention is a new process for the production of a large number of dialkyl N,N-dialkoxymethylcarbamylphosphonates in good yields.

Another object of this invention is the new dialkyl N,N- dialkoxymethylcarbarnylphosphonates.

These and other objects are achieved and dialkyl N,N- dialkoxymethylcarbamylphosphonates having the general formula (I):

wherein the individual radicals R and R may be identical or different and each denotes an aliphatic radical, moreover the two radicals R may denote, together with the adjacent oxygen atoms and the phosphorus atom, a five-membered or six-membered heterocyclic ring, R de notes a hydrogen atom, an aliphatic radical, a hydroxyl group or a halogen atom and n denotes zero, 1, 2 or 3 are 3,830,885 tented Aug. 20, 1974 obtained by reacting a dialkyl carbamylphosphonate hav= ing the general formula (II); I

or a dialkyl N-methylolcarbamylphosphonate having the general formula (III):

or a dialkyl N-alkoxy'methylcarbamylphosphonate having the general formula (IV):

'R OI-I (V) where R has the meanings given above in the presence of an acid in a second stage. I

When dimethyl 2- earbamylethanephosphonate and methanol are used, the reactions may be represented by the following equations;

0 I CH O I CHQ CHa OONHs 1 2CH O base CHs JI'IQO H I QCIIsOI-I sold 0 CH: 0- -CHr-Clir-O 0 N"GIIIO CH3 B 211.0 CH3( )HQOCH:

Having regard to the state of the art, the process ac cording to the invention surprisingly gives a large number of dialkyl N,N-dialkoxymet'hylcarbamylphosphonates in good yields. In particular it could not have been expected that N,N-dialkoxymethyl compounds would form at all in any significant amount and would not be decomposed again into their starting materials and under the acid conditions chosen no hydrolysis of the phosphonates would take place.

Dialkyl carbamylp'hosphonates and their monomethylol or monoslkoxyrnethyl compounds having the general formulae (II), (III) and (IV) are used as starting materials. Starting materials (III) may be obtained by reacting start:

ing materials (11) with formaldehyde. Startin materials fer-red starting materials (II), (III), and (IV) (and "I Q. accordingly preferred end products (I)) are those in whose formulae the individual radicals R and R are identical or different and each denotes an alkyl radical having one to six carbon atoms, preferably one to three carbon atoms, or an alkenyl radical having three to six carbon atoms, moreover the two radicals R together with the two adjacent oxygen atoms and the phosphorus atom may denote a five-membered or six-membered heterocyclic ring, R denotes a hydrogen atom, an alkyl radical having one to five carbon atoms, a hydroxyl group, or a chlorine or bromine atom and n denotes zero, 1 or 2. In each case the said radicals may be linear or branched and may hear one or more atoms and/ or groups which are inert under the reaction conditions, for examplehalogen atoms, preferably chlorine or bromine atoms, hydroxyl groups, or alkoxy groups having one to three carbon atoms, as substituents. When n denotes 2 or 3, the individual radical R may be identical or different.

For example the following starting materials (II), (III) or (IV) may be used in the reaction:

dimethyl 2-carbamylethanephosphonate,

diethyl 2-carbamylethanephosphonate,

dimethyl Z-carbamylpropanephosphonate,

dimethyl Z-carbamyl-1-chloroethanephosphonate,

diisopropyl carbamylrnethanephosphonate,

diethyl carbarnylphosphonate,

dihexyl carbamylphosphonate,

diallyl carbarnylphosphonate,

dibutyl 2-carbamyl-lhydroxypropanephosphonate; and

corresponding N'monomethylol, N-monomcthoxymcthyl and N-monoethoxymethyl compounds.

The starting materials (II), (III) and (IV) are reacted with at least an equivalent amount of formaldehyde, with reference to the replaceable hydrogen atoms in the amid group of the starting material (II), (III) or (IV), in the first stage of the process. Generally from 2 to 5 moles of formaldehyde is used in the case of diallcyl carb'amylphom phonates having the general formula (II) and in the case I of N-monomethylol compounds (III) and I-l-rnonoalkoxymethyl compounds (IV) from 1 to 4 moles of formaldc dehyde is used per mole of starting material. Formaldehyde may be supplied to the reaction as an aqueous solution or in the form of paraformaldehyde.

The first stage of the process is carried out in the pres ence of a base, preferably an alkali metal hydroxide or an alkaline earth metal hydroxide, for example sodium hydroxide, calcium hydroxide; alkali metal carbonates, for example sodium carbonate; tertiary amines, for example triethylamine, dimethylethanolamine, or pyridine. The base is generally used in an amount of from 0.5 to by Weight with reference to the starting material (II), (III) or (IV). The reaction takes place as a rule in the presence of a solvent which is inert under the reaction conditions such as water; aromatic hydrocarbons, for example benzene or toluene; ethers, for example dioxane or tetrahydrofuran; or mixtures of these. It is advantageous to carry out the reaction in highly concentrated solutions, for example from 70 to 98% by weight, particularly from 80 to 95% by weight, solutions of the starting material. (II), (III) or (IV) in the said solvents.

The result of the first stage of the process is a reaction mixture which in the case of starting material (II) contains the corresponding N-monomethylol compound, formaldehyde and the corresponding N,N--dimethylol compound. The reaction mixture in the case of starting material (III) has a similar composition while in the case of starting material (IV) the corresponding Nunethylol- N-alkoxymethyl derivative is present as well as the N-- alkoxymethyl compound and formaldehyde.

The reaction mixture formed in the first stage is then reacted in a second stage with an alltanol having the gen eral formula (V) in the presence of an acid. Preferred iii" alkanols (V) (and consequently preferred end products (1)) are those in whose formula R has the preferred meanings given above, for example methanol, ethanol or isopropanol. The alkanol (V) is used as a rule in at least the stoichiometric amount with reference to starting material (II), (III) or (IV), or preferably in an excess of twice to ten times. When a starting material (IV) is used, the reaction mixture is advantageously reacted in the second stage of the process with an amount of the alkanol (V) equivalent to the alkoxymethyl group of the starting material (IV).

The acid required for the second stage of the process may be an inorganic acid, for example sulfuric acid, hydrochloric acid or phosphoric acid, or an organic acid, for example oxalic acid, phthalic acid, benzenesulfonic acid or p-toluenesulfonic acid. Generally it is used in an amount of l to 10% by weight with reference to the amount of starting material (II), (III) or (IV) on which the reaction mixture is based in addition to the amount of acid required to neutralize the alkaline mixture (first stage). The alkanol (V) and all or part of any solvent used in the first stage generally serve as the solvent for the second stage. Further amounts of these solvents may be added if desired.

Both the first and second stages of the process are carried out as a rule at a temperature of from 0 to 100 (3., preferably at from 20 to 60 0., at atmospheric or superatmospheric pressure, continuously or intermittently.

The two stages of the process may be carried out follows:

A mixture of starting material (II), (III) or (IV), formaldehyde, base and if; desired solvent is kept for from two to five hours at the reaction temperature. The mixture may then be neutralized with acid and/or concentrated. Alkanol (V) and acid are then added and the resultant mixture is kept at the reaction temperature for from one hour to three hours while mixing well. The mixture is then neutralized and the end product is separated by a conventional method, for example by fractional dis tillation or crystallization.

The new compounds which can be prepared by the proccss according to the invention are assistants, particularly flamcproofing additives, for surface coatings and plastics and are valuable starting materials for the production of such assistants. For example a flame resistant coating may be achieved in metals by brushing the metal part with a mixture of parts of a conventional aminoplast resin, for example a mclamin-formaldehydc-butanol condensation. product, and 10 parts of a diallcyl N,N-dialkoxymethyh carbamylphosphonute with an addition of a hardening agent and baking the coating for some minutes at from 150 to 280 C.

The following Examples illustrate the invention.

Parts given in the Examples are by Weight.

EXAMPLE 1 A mixture of 724 parts of dirncthyl 2-curbamylctlnuu2- phosphonate, 240 parts of paraformaldchyde and 80 parts of 25% by weight caustic soda solution is heated for two hours while stirring at 50 C. in an iuipzuntus fitted with a stirrer. The reaction mixture is then concentrattnl to a. weight of 990 parts under sulmtmosphcric pressure. The syrupy residue has added to it 2.500 parts of methanol and parts of concentrated hydrochloric acid and the whole is heated at 45 to 50" C. While stirring. The mixture is then neutralized with caustic soda solution, the deposited sodium chloride is filtered oh? and the excess methanol and the water or reaction formed are distilled oli at sub atmospheric pressure. .979 parts (91% of the theory) of dimethyl N.N dimethoxynicthylcarhnrnylethsncphosphonate is obtained as a liquid crude product. The boiling 6 point (with decomposition) is 112 to 122 C. at 0.1 mm. pressure. 260 parts (91% of the theory) of dimethyl N, Analytical data: C H O NP (269): N-dimethoxymethyl 2-carbamyl-2-hydroxyethane-1-phos- Analysis (percent) Calculated Found C H O N P CHzQ 00112 G H O N P CHzO OCH; 40.2 7.44 35.7 5.2 11.52 22.3 46.1 39.8 7.4 36.0 5.3 11.6 21.8 45.4

EXAMPLE 2 phonate is Obtained. The product cannot be distilled in a A mixture of 179 parts of 2-oxo-2-(fi-carbamylethyl)- high vacuum because it decomposes. C H O NP (285):

1,3,2-dioxaphospholane, 60 parts of paraformaldehyde and EXAMPLE 5 parts of aqueous caustic soda solution is heated in a stirred apparatus for three hours at from 45 to 50 C. while stirring. Then the reaction mixture is added to a mixture of 600 parts of methanol and parts of con- HZOCFHTCH centrated hydrochloric acid and heated for two hours 2 OH; while stirring at 45 C. The reaction mixture is neutralized A mixture of 724 parts of dimethyl 2-carbamylethanewith concentrated caustic soda solution. The deposited l-phosphonate, 240 parts of paraformaldehyde and 80 sodium chloride is filtered off. The excess methanol and parts of 25% by weight aqueous caustic soda solution is the water of reaction are evaporated at subatmospheric heated while stirring at 50 C. for two hours in a stirred pressure. 260 parts of 2-0Xo-2-(N,N-dimethoxyrnethyl- 3- 25 apparatus. The reaction mixture is then concentrated to a carbamylethyl) 1,3,2- dioxaphospholane is obtained as Weig of 990 Parts at subatrnospheric pressure and 50 crude liquid product. This is equivalent to ayield of 97.5% to 5 Parts of isopfopanol Which Contains of the theory. The product cannot be distilled in a high p f hydrogen chloride is addfid t0 the y p residue vacuum because decomposition begins at about 125 WhlCh lS then heated for two hours at from to C. 30 The reaction mixture is then neutralized with caustic soda.

solution, the deposited sodium chloride is filtered off and O the filtrate is evaporated under subatmospheric pressure \f at a bath temperature of from 60 to 70 C. 1,080 parts P-OH2CHzGON-CHaOGHa (83% of the theory) of dimethyl N,N-diisopropoxymeth- HIOQH3 35 yl-2-carbamylethane-l-phosphonate is obtained. The prod- 0 uct cannot be distilled in a high vacuum because it de- EXAMPLE 3 composes from 130 C. 0 I claim: 1g 1. A dialkyl N,N-dialkoxymethylcarbamylphosphonate CBIaCHBO- GHICH'-CON CHIOCZH5 having the formula OBnCH H, Hfl oi il R OP(OH)=.OCNCHgOR A mixture of 69.6 parts of di-fl-trihromoethyl 2-car= -O R oHioR r bamylpropane w l-phosphonate, 6 parts of paraformalde- 45 Where the individual radicals R and R may be identical y and 10 Parts of a 25% y Weight aqueous Caustic or different and each denotes an unsubstituted alkyl rad soda solution is heated in a stirred apparatus for three i l having one t ix bo atoms or an alkyl r dical hours all With agitation Then 400 Parts Of ethanol having one to six carbon atoms which bears one or more containing 20 parts of hydrogen chloride is added to the halogen toms, hydroxyl groups and/or alkoxy groups reaction solution, and the whole is heated for three hours 50 having one to thr e carbon atoms as substituents or an at from 35 to 40 C. The reaction mixture is neutralized alkylene radical havin three to six carbon atoms, and with caustic soda solution, the deposited sodium chloride moreover h t o radic ls R together i h th adjacent is filtered off and the filtrate is evaporated at 50 C. in a oxygen atoms and the phosphorus atom may denote a water j Vacuum- After hiiving Stood for {W0 y t five-membered or six-membered heterocyclic ring, R de-= the end Product is deposited in crystalline form. t is notes a hydrogen atom, an alkyl radical having one to five filtered Off, dried and recrystallized from ethanol. 21 parts carbon atoms, a hydroxyl group, a, chlorine atom or a of di fi-trihromoethyl N,N-diethoxymethyl-2-carbamylbromine atom, and n denotes zero; 1, 2 or 3.

propane-l-phosphonate is obtained. This is a yield of 26% 2. A compound as in claim 1 wherein the individual of the theory. radicals R and R may be identical or different and each EXAMPLE 4 denotes an unsubstituted alkyl radical having One to six carbon atoms and R denotes hydrogen and n denotes 1, 2. 3. A compound as in claim 1 wherein the individual a0i-CHi-CE-OoN-GHMOHi radicals R and R denote methyl, R denotes hydrogen,

CH3 H 11200113 and n denotes 2.

References Cited 197 parts of dimethyl 2-carbamyl-2-hydroxyethane-1-.

phosphonate, 60 parts of paraformaldehyde and 20 parts UNITED STATES PATENTS of a 25% aqueous sodium hydroxide solution are heated 3,265,773 8/1966 LOSQO aL 260-9 at 50 C. for two hours while stirring. 500 parts of metha- 3,381,052 4/ 1963 Zahll w X 1101 containing 30 parts of concentrated hydrochloric acid 3,639,539 2/1972 Nachbllr c m." 260-943 X is added to the reaction mixture while stirring. The whole I is heated for another two hours at 50 C., cooled to room ANTON SUTTO, Pnmary Examlnel temperature and neutralized with concentrated caustic soda U S C1 X R solution. Deposited sodium chloride is filtered off and the methanol filtrate is concentrated under subatmospheric 106-15 FP; 260-937, 968

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3,830,885

DATED August 20, 1974 INV ENTOR(S) Harro Petersen It is certified that error appears in the above-identified patent and that said Letters Patent Q are hereby corrected as shown below:

In the heading, insert-Claims priority, Application German, September 27, 1968, P 17 93 5l4.7--.

Signed and Scaled this seventh Day of October 1975 [SEAL] AIIGSI.

RUTH C. M AHSON C. MARSHALL DANN' Altestmg Officer (ummissiuner of Parents and Trademarks O 

